Air-feed control for rock drills



W. A. SMITH.

AIRYFEEDAC'ONTBOLI FOR ROCK DRILLS. APPLICATION men DEC, 6. 1920.

Patented Feb. 14, 1922. fry/O INVENTOR UNITED STATES PATENT QFFICE.

WILLIAM A. SMITH, or rnILLIPsBUnG, NEW JERSEY, ASSIGNOB r0 INsnnsoLL-nAnn COMPANY, or JERSEY CITY, NEW JERSEY, A conroan'rron on NEW JERSEY,

AIR-FEED CONTROL FOR ROCK DRILLS.

Specification of Letters Patent.

Patented Feb. 14, 1922.

Application filed December 6, 1920. Serial No. 428,694.

d inarily wishes to maintain full rotation and hammer power with reduced air feed, when going through a soft spot for instance. The operator should also be able to reduce the power of theair feed quickly, because delay may mean that the drill will stick. With the usual air feed controlling device provided on stope drills, the operator must hold the handle provided on the machine with one hand and adjust a throttle or other controlling device with the other hand, and he may not do thls quickly enough to avoid trouble. The primary ob ects of the present mvention, as in my c'o-pending application, Se-

rial No. 400,979 filed August 3, 1920 are to enable the operator to quickly reduce the power of the air feed with full rotation and hammer power and effect this regulation and control without changing his grip on the machine. In the said application for patent, I showed and described a spring pressed valve for regulating the pressure in the feeding element, and a fluid pressure plunger normally tending to force the operating handle of the machine into a position to permit the regulating valve to close, whereby a given resistance to rotation during drilling will cause sufficient relative movement be tween the drill casing and the handle to cause the handle to open the valve and reduce the fluid pressure in the feeding element.

In accordance with the present invention,

inafter appear and to all of these ends the invention consists of the combinations of elements and features of construction shown in their preferred form in the accompanying drawings, in which-- V Figure 1 is a side elevation partly in vertical section of a rock drill embodying the invention,

Figure 2 is an enlarged detail top plan view of the drill partly in horizontal section on the line 2-2 of Figure 3. Figure 2 1s also a view partly in horizontal section on the line 2-2 of Figure 4,

Figure 3 is a detail side elevation partly in vertical section of the parts shown in Figure 2, and I b Figure 4; is a detail transverse vertical sectional view on the line 4t4c of Figure 2 looking in the direction of the arrows.

Referring to the drawings, Figure 1 illustrates a stope drill to which the invention is applied having a cylinder A provided with the usual front head B carrying the drill steel C. The drill steel may be rotatedby any suitable means, in this instance a rock drill of the independent rotation type being shown having a rotation motor casing D. The cylinder A with its operative parts for imparting the impact blows of the piston hammer tofthe drill steel C comprises the percussive element of the machine;

The feeding element is shown as the usual air feed cylinder E having the piston F and the piston rod G provided with the rock ongaging point H. Between the cylinder A and the air feed cylinder E is preferably arranged in this instance the head block K, the parts of the machine being held together by the usual side bolts L. Fluid pressure is admitted to the percussive and feeding ele ments through the inlet 0 controlled by the throttle P having the throttle handle Q.

In order to regulate the air pressure in the feeding cylinder E in accordance with this invention, I prefer to provide controlling means having an exhaust passage R leading fron'i the feed cylinder to a valve chamber S in the projecting portion T of the head block K, communicating with the atmospheric port U. The valve chamber S is preferably closed at the outer end V and a valve at having a spring a and a plunger head 6 operates in said valve chamber S and is normally maintained in closed position as indicated in Figure 2 bythe spring and fluid pressure on the inner pressure surface 0 of the valve, due

to the live pressure admitted through the passage (Z communicating with the throttle P. The spring a may be omitted, but is preferable because the valve is held in closed position when the air is off. The machine is provided with an outwardly extending handle W, commonly called the rotation handle, in this instance having the gripping projection TV at right angles thereto and extending downwardly, adapted to be grasped and held by the hand of the operator. The handle XV is connected to the easing in any suitable manner so that it may be rotated through a limited angle about its longitudinal axis. In this instance the handle is rotatably held in a socket X in the head block K. A stop Y on the handle limits the angular movement in one direction by striking against the head block K. The plunger head Z) of the valve a bears against the handle and normally tends to push or rock the handle away from the head'block into the position indicated in Figure 2 and this outward rocking movement of the handle is limited by the stop Y.

In the operation of the machine, the air teed cylinder regulator orrclief valve (6 is normally closed and the handle V is in the position indicated in Figure 2. The operator maintains his hand on the handle and the plunger head Z) and valve a will be forced inwardly and allow the handle V to open the valve (1, when the rotation becomes overloaded or at the sticking point of the rotation, due to the torque on the machine 7 under resistance to rotation. The inward opening movement of the valve at will release the air feed and cause the machine to in clean, cutting ground, but it-will relax and drop back automatically according to the resistance to rotation. Another important feature in regard to this automatic ac tion resides in the fact that the machine will push up in soft ground as long as the resistance to rotation does not become too heavy and it will not wait for the drill to stick before the air feed begins to release, so that the action is quicker than in the case of hand control.

If the miner desires, he may at any time,

by making a quick pull on the handle XV open the air feed release valve 6!, but this operation would ordinarily not be required since the machine is entirely automatic in action as long as the operator has his hand on the handle W.

Obviously other forms of devices may be designed to carry out the function of the fluid actuated air feed release valve a for cooperating with the working handle, and I am not to be understood as limiting the invention toa pressure actuated device having a valve head and a plunger, and furthermore the valve and the plunger need not be formed in one piece and the drawing may be taken to indicate either a one piece valve and plunger or a device having more than one piece, as desired.

I claim:

1. A rock drill having a percussive element and a fluid pressure feeding element, a valve constantly subjected to fluid pressure for regulating the pressure in the feeding element and manually controlled means cooperating with said valve and dependent upon the resistance to rotation for controlling said valve, whereby the feeding element is automatically regulated in accordance with the requirements of the work.

2. A rock drill having a percussive element and a fluid pressure feeding element, avalve constantly subjected to fluid pressure for regulating the pressure in the feeding element, a handle movable relatively to the valve against said fluid pressure and adapted to be grasped by the operator, a given resistance to rotation in'drilling causing the handle to operate the valve and automatically reduce the pressure in the feeding element in accordance with the requirements of thework.

8. A rock drill having a percussive eleduring drilling will automatically cause relative movement between said members and reduce the pressure 1n the feeding element in accordance with the requirements of the work. 1

4. A' rock drill. having a percussive ele-' mentand a fluid pressure feeding element, a valve constantly subjected to fluid pres sure for regulating the pressure in the feed ing element, said valve being normally closed, a handle pivotally connected to the drill casing and adapted to control said valve, the fluid pressure against the valve normally tending to force said handle into a position to permit the valve to close, whereby a given resistance to rotation during drilling will cause sutiicientrelative movement between the drill casing and the handle to cause the handle to open the valve against pressure and reduce the fluid pressure in the feeding element. 7

5. A rock drill having a percussive element and a fluid pressure feeding element, a valve constantly subjected to fluid pressure tending to close it, mounted in the drill casing for regulating the pressure in the feedin element an outwardl extendin handle pivoted to the drill casing and adapted to be grasped by the operator for controlling the saidvalve, the fluid pressure through 10 the agency of the valve normally tending to force said handle into inoperative position with relation to the valve whereby a given resistance to rotation during drilling will cause sufiicient relative movement between the drill casing and the handle to cause the handle to operate the valve and reduce the fluid pressure in the feeding element.

In testimony whereof I have signed this specification.

WILLIAM A. SMITH. 

